Cathode ray tubes or the like -



Aug. 11, 1959 c. w. GEER 2,899,579

CATHODE RAY TUBES OR THE LIKE I Filed June 21, 1954 I 10 Sheets-Sheet 1'CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER 7 2,899,579

CATHODE RAY TUBES OR THE LIKE Filed June 21, 1964 10 Sheets-Sheet 2 ITEi E! g I CHARLES WILLARD GEER INVENTOR. =I T 6 svflw-w HlS ATTORNEY"Aug. 11, 1959 c. w. GEER Y CATHODE RAY TUBES OR THE LIKE 1 1OSheets-Sheet 3 Filed June 21. 1954 CHARLES WILLARDGEER IN VEN TOR. BYflwM HIS ATTORNEY Aug. 11, 1959 c; w, GEER 2,899,579

CATHODE RAY TUBES OR THE Lmz Filed June 21. 1954 1o Sheets-Sheet 4CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER CATHODE RAY TUBES OR THE LIKE 10Sheets-Sheet 5 Filed June 21, 1954 '7-"--------1'--'--;}-----------"FflCHARLES WILLARD GEER ,9 INVENTOR. gyflual HIS ATTORNEY Aug. 11, 1959 c.w. GEER CATHODE RAY TUBES OR THE LIKE l0 Sheets-Sheet 6 Filed June 21,1954 CHARLES WILLARD GEER INVENTOR. BY a-M HIS ATTORNEY Aug. 11, 1959Filed June 21, 1954 c. w. GEER 2,899,579

- CATHODE RAY TUBES OR THE LIKE 1O Sheets-Sheet 7 CHARLES WILLARD GEERINVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEER CATHODE RAY TUBES OR THE LIKE 10Sheets-Sheet 8 Filed June 21, 1954 CHARLES WILLARD GEER INVENTOR. syfifiHIS ATTORNEY Aug. 11, 1959 c. w. GEER 2,899,579

CATHODE RAY TUBES OR THE LIKE Filed June 21, 1954 10 Sheets-Sheet 9CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY Aug. 11, 1959 c. w. GEERY CATHODE RAY TUBES OR THE LIKE l0Sheets-Sheet 10 Filed June 21, 1954 CHARLES WILLARD GEER INVENTOR.

HIS ATTORNEY United States Patent 2,899,579 CATHODE RAY TUBES on THELIKE Charles Willard Geer, Long Beach, Calif., assignor to HoffmanElectronics Corporation, a corporation of California Application June21, 1954, Serial No. 438,096

12 Claims. (Cl. 313--81) This invention relates to improvements incathode ray tubes and, more particularly, to an improved structure forthe reproduction of television images in natural color. In the pastnumerous devices and systems have been proposed for color televisionreproduction, but such apparatus has suffered from defects which fallinto four main categories. First, the definition available with cathoderay tubes utilizing a single gun and bands of difierent colored phosphorhas proven, generally, poor and the grain or line structure has beenvery objectionable. Further there are undesired effects from the gridswitching usually found in tubes of this type. Second, in tubesutilizing parallax grids or shadow masks'the high loss of electrons atthe shadow mask has resulted in low line intensity from the tubes.Third, tubes utilizing three guns and, for example, a screen formed ofpyramidal elements, such as that shown and described in my Patent No.2,480,848, have been bulky in form and not easily adaptable to hometelevision receiver cabinetry. Fourth, a characteristic particularlyexistent in the shadow mask type of tubes is the high cost ofmanufacture arising from the familiar problems of obtaining alignment orregistration between the shadow mask and the various color producingphosphors.

Therefore, it is an object of this invention to provide an improvedcathode ray tube for reproduction of images in color.

It is a further object of this invention to provide a color televisionreproducing tube which affords high definition and freedom fromobjectionable line structure at a minimum cost and with a form factorwhich makes the tube adaptable to home receiver use.

It is a further object of this invention to provide a relativelylow-cost color television reproducing tube in which certain of the gridstructures may be formed by low-cost weaving techniques.

According to one embodiment of the present invention, there is provideda cathode ray tube utilizing multiple cathode ray guns arranged inparallel fashion within the neck of the tube and in which the screen isformed of a multiple of pyramidal elements of the tyme utilized in thestructure according to my Patent No. 2,480,848. Interposed between theelectron guns and the screen are three grids, the first of which acts asa parallax-convergence or convergence and positioning grid. The secondof such grids counting from the gun side to the screen side is anelectrostatic deflection grid charged from an external source so as todeflect the impinging electron beams in a predetermined direction. Thethird of such grids which is spaced relatively closely to the second ofsuch grids completes the beam deflection process as a result of itsbeing charged with an appropriate static potential. A

corresponding deflection may be effected by electromag-' lieved to benovel are set forth with particularity in the appended claims. Thepresent invention, both as to its organization and manner of operation,together with further objects and advantages thereof, may best be under=stood by reference to the following description, taken in connectionwith the accompanying drawings, in which:

Figure 1 is a side elevational view, partially in section, showing oneembodiment of the invention;

Figure 2 is a cross-sectional view taken along line 22 in Figure 1;

Figure 3 is a view taken along line 33 in Figure 1;

Figure 4 is an enlarged view of a portion of the grid structure shown inFigure 3;

Figure 5 is a sectional view taken along line 55 in Figure 1 showing themost proximate grid;

Figure 6 is an enlarged view of a portion of the outermost grid shown inFigure 5;

Figure 7 is a sectional view taken along line 77 in Figure 1;

Figure 8 is an enlarged view of a portion of the grid shown in Figure 7;

Figure 9 is a sectional view taken along line 99 in Figure 1;

Figure 10 is an enlarged view of a portion of the screen or electrontarget shown in Figure 9;

Figure 11 is an enlarged perspective view showing the relativeorientation of the grid structures shown in Figures 3, 5 and 7, and, inaddition, showing the orientation of a segment of the screen structureof Figure 9 associated with the enlarged portion of the grid;

Figure 12 is a side elevational View, partially cut away, of a secondembodiment of the invention;

Figure 13 is a cross-sectional view taken along lines 13 -13 in. Figure12;

Figure 14 is a sectional view taken along line 14-14 in Figure 12showing the most proximate grid;

Figure 15 is an enlarged view of a portion of the grid structuredisclosed in Figure 14;

Figure 16 is a sectional view taken along line 15-46 in Figure 12showing t e m pro t gr d;

Figure 17 is an enlarged view of the Portion of the grid structure shownin Figure 16;

Figure 18 is a sectional view taken along line 18.- 1 8 in Figure 12showing the most proximate grid;

Figure 19 is an enlarged view of a segment of the grid structure shownin Figure 18;

Figure 20 is a sectional view taken along line 20-- 20 in Figure 12;

Figure 21 is an enlarged view of the segment of the target structureshown in Figure 20;

Figure 22 is a perspective view showing the relative orientation of thegrid structures and screen structure according to this invention;

Figure 23 is a diagrammatic representation of a twogun embodiment of thepresent invention;

Figure 24 is a diagrammatic representation of an additional embodimentof a four-gun cathode ray tube utilizing electromagnetic rather thanelectrostatic deflection;

Figure 25 is an enlarged view of a portion of the grid structure shownin Figure 24; and

Figure 26 is a view, partially in schematic form, of the deflection gridof Figure 24.

In Figure 1, a beam of electrons is generated in the electron guns 10and 11, which are shown in Figure 1, and in two additional electron guns20 and 21 not visi- Me in Figure 1 but visible in Figure 2. Theseelectron guns are of the conventional variety utilized in cathode raytubes and includes the necessary cathodes, control grids andaccelerating electrodes, which are not shown because of theirconventional nature. Electrons from each of the guns first pass throughapertures in grid 12 which is positioned and tensioned by support member13. The function of this first grid is to converge the electron beamsand position each of the beams at the appropriate point on grid 14. Torealize those effects, this grid is maintained at a negative potential.The term parallax-convergence grid as used throughout the specificationand claims is intended to mean a unitary or composite grid which is soconstructed and positioned within the cathode ray tube as to, uponapobserver views the side of target structure remote from the phosphoredsurfaces, hence, the target struc/ ture must be transparent. Grid 16,which is in close proximity to grid 14, is also a deflection grid andsupplements the initial effect produced by grid 14, further assuring theproper impingement of the electron beams on target or screen 15. Therelative positioning of grids 12, 14 and 16 is assured by the rigidnature of support member 13 of this multiple grid assembly and supportmember 13 is in turn supported from envelope 17 by means of supportelements 18 and 19.

In Figure 2, the relative orientation of the four guns utilized in thisembodiment of the invention is shown. Gun 20 is positioned so that theelectrons emanating from it impinge upon the blue-producing phosphor oftarget 15. Correspondingly, electrons from guns 21, 22 and 23 impingeupon the red, white and green phosphors, respectively, of the targetstructure 15. In Figure 3, grid 12 may be stamped, electro-formed orwoven by well known and economical techniques. For purposes ofdiscussion grid 12 is considered to have been made by a weaving process,as may be more clearly determined by reference to the enlarged view inFigure 4. Because of the common potential of all of the conductors 40the grid may be woven from bare wire of the appropriate dimensions, andbecause of the high degree of vacuum existing in the cathode ray tube,no problem of corrosion exists. Techniques are well established forweaving metal wire of small diameter and the process if simple andinexpensive.

An indication is also made in Figure 4 as to the points of impingementof the electron beams emanating from the various guns. As can be seen,the beams may impinge upon separate apertures and several at one time.Such positioning is not critical to the degree that positioning iscritical in present day shadow mask tubes. Thus, the grid need not beconstructed to extremely high tolerances and with a reasonable amount oftensioning in support member 13 and with proper orientation with respectto subsequent grids 14 and 16, which will be discussed later, properfunctioning of the cathode ray tube may be realized. Grid 40 ismaintained at a negative potential so that the beam of electronsimpinging upon it from each of the guns is condensed or converged and,at the same time, positioned in some degree.

In Figure 5, grid 14 is of a conductive material and may be formed bystamping, electro-forming or by weaving. Once again, the grid has beenshown as woven, which is more evident in the enlarged view of .Figure 6.

The purpose of this size differential will become more 'from theirapexes. the invention the pyramids are quadrahedronal, each In Figure 6,the points of electron beams impinging on grid 14 or its interstices areindicated. Grid 14 is maintained at a positive potential so as toattract the electron beams towards the grid elements 60. Thus, the beamsmust fall in the region of the intersection between grid elements and onthe indicated sides of diagonal bisectors of each of the apertures ofinterstices, as indicated. Thus, in Figure 6, each of the red, green,white and blue electron beams will be atttracted towards intersection61. An initial deflection of each of the electron beams is thuseffected.

In Figure 7, grid 16 is composed of intersecting grid elements which maybe formed by stamping, electro-forming or weaving. Once again the gridsare shown as having been formed by a weaving technique. This is evidentin Figure 8, the enlarged view. Once again the grid elements 70 are alloperating at a common potential so that no insulating problems exist andthe grid may, be woven from bare conductive wire. The relative positionsof the electron beams impinging on grid 16 are indicated in Figure 8.Grid 16 is maintained at a negative potential so that it repels the.beams of the electrons.

Its orientation with respect to grid 14 is more clearly indicated inFigure 11, but generally this grid 16 is displaced one-half the width ofone of its interstices in both the horizontal and vertical directions sothat grid element 70 effectively bisects the interstices of grid 14 ifthe two grids 14 and 16 are viewed either from the gun side of the gridcombination or from the target side. Grid 16 thus provides theadditionally required deflection of each of the electron beams to insureimpingement on the proper portions of target or screen electrode 15.

In Figure 9, the relative positioning of the various pyramidal screenelements is shown. It is to be realized that in this figure the pyramidsare viewed substantially In this four gun embodiment of of the foursides carrying a phosphor which produces one of the desired colorcomponents. This orientation of the pyramids and the different colorphosphor is exhibited more clearly in Figure 10 wherein the standarddesignation for each of the primary colors and white are utilizedshowing the deposition of the phosphors on the various sides of thepyramids.

In Figure 11, the relative positions of grids 12, 14 and 16 and targetor screen electrode 15 and the spacings are indicated. It is to be notedthat grid 12 is spaced from grid 14 a distance which is substantiallygreater than the distance from grid 14 and 16. This spacing is afunction of a number of factors, as follows.

By reason of the displacement of each gun from the common center betweenthe guns the familiar phenomenon of parallax occurs and the electronbeam from each gun has an angle of incidence upon a given interstice inconvergence grid 12 which is different from that of the beam from eachother gun. The establishment of a negative potential on grid 12 resultsin converging each incident beam and confining its point of passagethrough grid 12 to a common point in each interstice, which issubstantially the geometrical center of each interstice. As the beamsare scanned over the entire surface of grid 12 they move in discretesteps from aperture to aperture by reason of the negative potentialmaintained on grid 12. However, by reason of the aforementioned parallaxeffect, despite the shifting of each beam to such geometrical center,each beam emerges from grid 12 at an angle different from'that of eachother beam and the beams remain separate as they fall upon predeterminedpoints on the succeeding deflection grid 14. The points at which thebeams fall in any given aperture in grid 14 are determined by the anglesof incidence, and the separation between grids 12 and 14.

From Figure 11 it may also be seen that the spacing of successive gridelements 40 is approximately one-half the corresponding spacing of gridelements 60 of grid 14 and, hence, the size of the interstices in grid12 is onehalf the size of the interstices in grid 14. Also, it should benoted that whereas the outermost of grid elements 40 and 60 liesubstantially in a plane normal to grids 12 and 14, the outermost gridelement 70 of grid 16 is dis placed so that it does not lie directlybehind grid element 60 but is centrally disposed in the distance betweensuccessive grid elements 60 of grid 14. Thus, behind each grid element41) there lies either a grid element 60 or a grid element 70 but notboth, all as viewed from the electron gun side of the grid combination.It should be noted that the electron beam positions indicated in Figures6 and 8 represent, substantially, the point within the interstices wherethe indicated electron beam will fall as it passes over that interstice.However, at any one instant the electron beam from each of the electronguns may fall in different interstices but will fall in the indicatedquadrants of any interstice in which each beam falls. The ultimaterequirement is, of course, that the beam intended to produce each of theprimary colors and white should produce only each of such colorsthroughout the scanning of the combination of the beams across thescreen or target structure 15. To accomplish this the separation ofgrids 12, 14 and 16 and the potentials applied to each of these gridsmust be properly established. When that relationship is established,each of the beams emerging from the grid combination should have a maincomponent oriented approximately in a normal direction to the plane ofthe pyramid face bearing the phosphor which each such beam is intendedto excite. Once that relationship has been established, any movement ofthe entire grid combination in a plane parallel to the plane of thepyramid bases will produce no color infidelity because of the discretedirectional component of each of the electron beams. Thus, the complexregistry problem presently encountered in shadow mask or parallax-gridcolor tubes is eliminated.

As has been indicated, the exact point in the interstice upon which eachof the electron beams falls is not critical for a minor adjustment inthe electrostatic potentials on each of the grids can compensate for anyminor variations in the initial positioning of the beams on grid 12.

Further, the exact configuration of each aperture is not critical for areasonable amount of uniform tensioning in support member 13 so that thegeneral relative position of grid elements 40, 6t) and 70 is as alreadydescribed, is all that is required. Upon such adjustment and positioningof the grids, possibilities of color infidelity are slight with thisinvention.

It should be noted that the loss of electrons in the convergence ofbeams in grid 12 is slight because of the large open areas and the useof negative potentials to condense or converge the beam or to positionit as desired. In present parallax-grid tubes, a high electron lossoccurs because the apertures, of necessity, are very small, the

registry between the parallax grid and the phosphor elements beingextremely critical.

7 The foregoing description has dealt with a four-gun cathode ray tubecapable of reproducing the three primary colors plus white light energywhich corresponds to the brightness of any scene to be reproduced. It isentirely possible to reproduce an original image in natural color usingonly the three primary colors and applying brightness information toeach of the three guns producing the electron beams which ultimatelyproduce the three primary colors. A cathode ray tube utilizing thestructural principles of the present invention and capable ofreproducing images in natural color through the use of three primarycolors is shown in Figure 12 and details of that tube are shown insucceeding Figures 13 through 22. In Figure 12 cathode ray tube 126includes electron 1 guns 121, 122 and 123 which may be designated forthe purposes of this description as the blue, green and red electronguns, respectively. The exact orientation of flection grid 126 andsecond deflection grid 127, the shape and orientation of the variousapertures in those grids being shown more clearly in Figures 14 through20. As can be seen in Figures 12 and 22, the spacing between grids and126 is large with respect to the spacing between grids 126 and 127. Therelative positioning of the three grids is fixed and maintained by meansof support 128, which, in turn, is directly supported from envelope 129of cathode ray tube 120 through bracket element 130.

The cathode ray tube of Figure 12 operates substantially as follows. Abeam of electrons of the appropriate velocity is generated inconventional fashion by each of the guns 121, 122 and 123. These gunsmay include the conventional first accelerating anodes and focusingelectrodes, neither of which is shown. As can be seen from Figure 15,electrons from each of the guns pass through apertures in positioninggrid 125. These apertures are surrounded by conductive grid elements151, 152, 153, 154, and 156 which may be formed by weaving, as shown inFigure 15, or by stamping or electroforming. A negative potential isapplied to this grid so as to produce convergence of the impingingelectron beams. It is to be noted that at any one instant, the threeseparate electron beams may be passed through three separate apertures150 in grid 125 but when any one of the beams, for example, the redbeam, passes over a given interstice it Will pass through the grid at apoint having the indicated relationship with respect to the point ofpassage of the other beams. It is to be noted that by utilizing negativepotentials on this grid, it is possible to use a grid having arelatively large mesh while retaining the desired positioning efiect,thus reducing the loss of electrons which normally results from thestriking of the conductive members forming the boundaries of theapertures or interstices. Grid 125 may be woven from conductivematerial, as shown in Figures 14 and 15, stamped from conductivematerial or electro-formed.

Upon emerging from grid 125, each of the electron beams impinges upongrid 126, or more accurately, upon the apertures in grid 126. Therelative positions of the three beams in their respective traversals ofany one of the apertures in grid 126 are as shown in Figure 17. It is tobe noted that at any instant, the red, blue and green beams may not fallwithin the same aperture but, instead, may fall within aperturesseparated from aperture $170 as suggested by Figure 12, the onlyultimate requirement being that the beams impinge upon a commontrihedron or pyramid in target structure 124. As can be seen fromFigures 17 and 22 grid 126 is a composite grid including portion 126Apositioned closest to the electron guns and portion 126B spaced fromportion 126A along the electron path and further from the electron gunsthan portion 126A. A high negative potential is applied to portion 126Aand an equally high positive potential is applied to portion 126B. Thetwo grid portions obviously must be insulated from each other and thisis accomplished by insulating beads 157. The negative charge on portion126A begins the deflection of each of the electron beams. It should benoted that portion 126B has hexagonal apertures of approximately thesame size as portion 126A but the apertures of portion 126B aredisplaced from alignment with those of 126A one-half an aperture widthin one direction and one-half a diagonal length in an orthogonaldirection. The positive potential is applied to grid 126B so that thebeams of electrons are pulled towards elements 171, 172 and 173, asshown in '7 Figure 17. As a result of the fact that grid 126A is chargedas far negatively as grid 126B is charged positively, the netdeceleration of the electron beam through grid 126 is substantially zerowhile at the same time the desired discrete deflection of the respectiveelectron beams is effected.

The deflected beams emerging from grid 126 impinge upon grid 127, shownin its entirety in Figure 18, which grid may be of the same grid patternas grid 126 but is displaced both vertically and horizontally so thatthe intersection of elements 171, 172 and 173, shown in Figure 17, issubstantially aligned with the geometrical center of the aperture orinterstice 190 of Figure 19, shown bounded by elements 191, 192, 193,194, 195 and 196. This orientation is indicated in Figure 16.

Grid 127 is charged negatively and, partially by reason of the relativedisplacement between grids 126 and 127, accentuates the deflection ofeach of the electron beams so that upon emerging from grid 127 thosebeams have discrete and differing directions. The position of guns 121,122 and 123, as shown in Figure 13, is such that each beam takes adifferent path through grids 126 and 127 and falls upon a predeterminedface of a common trihedron which face carries the appropriate phosphorpossessing the ability to produce one of the primary colors. For optimumcolor intensity each of the beams should have substantially normalincidence upon its associated phosphor. The orientation of thetrihedronal elements forming target structure 124 is shown most clearlyin Figure 21. In that figure there is shown a segment of targetstructure 124, shown in its entirety in Figure 20, viewed from the lineof approach of the electron beams. Pyramidal element 210 has faces 211,212 and 213 bearing phosphors which produce red, blue and green lightenergy. As can be seen from Figure 12, to attain this normal incidenceof the electron beams upon the related phosphors utilizing thedeflection system of this invention, the three electron guns 121, 122and 123 may have a relatively wide angular displacement so that at anyone instant the beam from any one gun falls at a point on grid 125 whichis relatively widely separated from the point at which a beam fromeither of the other guns falls. This may necessitate having the grids125, 126 and 127 of greater area than target electrode 124.

If the beams from electron guns 121, 122 and 123 are scanned over thecomplete surface of target 124, the beams will fall upon thepredetermined sides of successive trihedronal elements making up thetarget electrode 124 and the originally scanned image will bereproduced. This scanning may be accomplished by any of the well knownelectromagnetic or electrostatic techniques. As has been indicated inconnection with the four-gun tube, minor discrepancies of aperture sizeand grid spacing are tolerable and may be easily compensated by voltageadjustments on grids 125, 126 and 127. Once again a high electronefliciency is realized because of the relatively wide spacing of thegrid elements in grid 125 and the utilization of the negative potentialthereon to accomplish the necessary convergence and initial positioning.The positioning of the grid combination with respect to the targetelectrode 124 is not critical, particularly as to lateral displacement,because of the discrete directions attained by the three electron beamsupon emerging from the grid combination and the corresponding discretedirections of the trihedron faces.

For certain applications, such as in radar, the combination of twoprimary colors may provide a sutficient range of hues to indicate thedesired information. The relationship of the electron guns, gridstructures and target electrode is shown in Figure 23. In that figureelectron guns 230 and 231 are of a conventional variety. Electron beamsemanating from those guns first fall upon a convergence and positioninggrid 232 the apertures in which have the general configuration of asquare or rectangle as shown in Figure 23. Convergence grid 232 is madeup of'conductive elements 233 and 234 which are charged to a commonnegative potential. After each beam emerges from convergence andpositioning grid 232, it falls in the area between successive elements235 and 236 of first deflection grid 237. In the structure shown inFigure 23 positioning grid 237 is charged negatively and by reason ofthe repulsion between the electrons and the negatively charged gridelements the electron beam is given an initial displacement as shown.Each electron beam upon emerging from grid 237 impinges upon grid 233which comprises elements 239 and 240 spaced the same distance aselements 235 and 236 but positioned midway between elements 235 and 236.This grid is charged positively and is spaced from grid 237 so that theattracting action of element 240 upon an impinging electron beam exceedsthat of element 239, the initial displacement produced by grid 237 isaccentuated and the beams emerging from grid 238 have discretedirections differing widely from each other and the beams approachsurfaces 241 and 242 of target 243 with approximately normal incidence,as shown. Once again, by reason of the discrete directions of motion towhich the electron beams have been confined and the correspondingorientation of the related phosphor laden surfaces, each gun will hitonly one set of surfaces on target 243 throughout the scanning process.

In the discussion of the four-gun tube shown in Figures 1 and 2, and, ineffect, in connection with the other color tubes thus far described,electrostatic deflection has been utilized to effect the desireddevelopment of separate electron beams having discrete and differentdirections. This same eflect can be realized by electromagneticdeflecting means. A possible embodiment is exhibited in various detailsin Figures 24 through 26. In Figure 24 convergence and positioning grid245 corresponds to convergence grid 12 in Figure 1 and accomplishes thesame results, namely convergence of the beam and positioning of itproperly on the deflection grid 246.

As can be seen from Figure 24 the electron beams from the four gunscluster about alternate vertical elements 247 in which currents areflowing in a direction such that they produce flux lines flowing in acounterclockwise direction. By applying well known principles ofelectron optics, more specifically the so-called lefthand rule, it canbe shown that electrons having the initial direction shown in Figure 24,namely a downward direction, will be deflected towards the axis of thewire adjacent which they are flowing. For a given orientation ofpyramidal elements 248, the four electron beams emerging from deflectiongrid 246 must have discrete and difiering directions related to suchpyramidal orientation. The convergent efiect of current carryingelements 247 with the aid of the effects produced by the fieldssurrounding elements 253 results in the acquisition by the four electronbeams impinging upon grid 246 of the necessary discrete directions. Asdescribed earlier, each of the faces of any one pyramid carries aphosphor exhibiting a different color response upon impingement of anelectron beam.

Further details of the deflection grid are indicated in Figure 26 whichshows the direction of the magnetic fields surrounding each of thevertical elements 247 and 253 constituting the deflection grid. Thesingle dot indicates the head of an arrow directed in the same directionas the current flow (upward here) and each x indicates the position ofeach vertical element in which the current flow is in a relativelydownward direction. By applying the left-hand rule it will becomeapparent that if the electron beams were directed downward towards thevertical elements in which the current is directed downward the beamswill be diverged rather than converged. As has already been indicatedthis effect aids the desired deflection fields produced by currentcarrying elements 247.

Because of the extended length of deflection grid 24,6

9 in the direction of the electron movement, it is not neces sary tohave a second layer of grids to realize the desired degree of beamdeflection. The successive rows of de- :flection elements forming thedeflection grid 246 may be joined electrically at alternate ends so asto require connection to a source of current of only the resulting twoopen ends of the grid.

- Convergence and positioning grid 245 may be formed by weaving,stamping or electro-forming.

It may be seen from the foregoing description that there has beenprovided a cathode ray tube for the reproduction of televised images innatural color which tube will provide a high intensity picture and alsowill be sufficiently compact to be adaptable for use in home televisionreceivers and which will be relatively simple and inexpensive tomanufacture by reason of the considerable reduction in the problem ofregistering the convergence and deflection grids with the targetstructure and with each other.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects, and, therefore, the aim in theappended claims is to cover all such changes and modifications as fallwithin the true spirit and scope of this invention.

I claim:

1. A cathode ray tube for presenting information in color, including aplurality of electron guns, a target structure including a plurality ofsets of faces, the faces within each set lying in parallel planes at anangle toward the initial direction of the beams from said guns, andmeans for causing impingement of the beams upon the target facessubstantially normal thereto including an apertured parallax gridbetween the guns and target for positioning the beams impinging thereonat similar locations in the apertures thereof, and a deflection gridbetween the parallax grid and target for deflecting the beams emergingfrom the parallax grid in a direction substantially normal to the targetfaces.

2. A cathode ray tube for presenting information in color, including aplurality of electron guns, a target structure including a plurality ofsets of faces, the faces Within each set lying in parallel planes at anangle toward the initial direction of the beams from said guns, andmeans for causing impingment of the beams upon the target facessubstantially normal thereto including an apertured parallax gridbetween the guns and target for positioning the beams impinging thereonat similar locations in the apertures thereof, and a deflection gridbetween the parallax grid and target for deflecting the beams emergingfrom the parallax grid in a direction substantially normal to the targetfaces, the number of such sets equalling the number of said guns.

3. A cathode ray tube for presenting information in color, including aplurality of electron guns, a target including a plurality ofmulti-hedrons with common orientation in which the sides are at an angletoward the initial direction of the beams from said guns, and means forcausing impingement of the beams upon the sides substantially normalthereto including an apertured parallax grid between the guns and targetfor positioning the beams impinging thereon at similar locations in theapertures thereof, and an electromagnetic deflection grid between theparallax grid and target for deflecting the beams emerging from theparallax grid in a direction substantially normal to the sides.

4. A cathode ray tube including four electron guns, a target including aplurality of tetrahedrons oriented to provide four sets of faces, eachset having a common direction differing from each other set, .a parallaxconvergence grid and first and second deflection grids interposed inthat order between said guns and said target along the line of movementof the electrons from said guns, said convergence grid havingsubstantially squareapertures therein of a first size, said firstdeflection grid having apertures therein of substantially squareconfiguration and of substantially twice the size of said convergencegrid apertures, said second deflection grid having apertures therein ofsubstantially the same size as said first deflection grid but displacedfrom alignment with the apertures of said first grid substantiallyonehalf the width of one of said apertures in said first deflectiongrid, the spacing between said convergence grid and said firstdeflection grid being greater than the spacing between said first andsecond deflection grids, and means for applying electrostatic potentialsto said convergence and deflection grids.

5. A cathode ray tube including four electron guns positioned at smallangles with respect to each other, a target including a plurality oftetrahedrons oriented] to provide four sets of faces, each set having acommon direction differing from each other set, .a parallax convergencegrid and first and second deflection grids interposed in that orderbetween said guns and said target along the line of movement of theelectrons from said guns, said convergence grid having substantiallysquare apertures therein of a first size, said first deflection gridhaving apertures therein of substantially square configuration and ofsubstantially twice the size of said con- Wergence grid apertures, saidsecond deflection grid having apertures therein of substantially thesame size as said first deflection grid but displaced from alignmentwith the apertures in said first deflection grid substantially one-halfthe width of one of said apertures in said first deflection grid, thespacing between said convergence grid and said first deflection gridbeing greater than the spacing between said first and second deflectiongrids, and means for applying electrostatic potentials to saidconvergence and deflection grids.

6. For use in a color television reproducing tube, a grid combinationincluding a parallax grid, and a deflection grid, said parallax gridbeing positioned with its interstices in substantial alignment with theinterstices in said deflection grid and spaced a predetermined distancefrom said deflection grid, said parallax grid being adapted for theapplication of a negative potential thereto, whereby electrons impingingupon said parallax grid from a given source will fall consistently onpredetermined portions of said deflection grid.

7. A cathode ray tube for reproduction of images in natural colorincluding a plurality of cathode ray guns clustered about a common axis,a parallax grid .adapted for connection to a source of negativepotential, a first deflection grid positioned parallel to said parallaxgrid and spaced therefrom .a predetermined distance, the interstices ofsaid first deflection grid being in predetermined relation to theinterstices in said parallax grid, whereby electron beams from each ofsaid guns fall consistently on predetermined portions of said firstdeflection grid, said first deflection grid being adapted for connectionto a source of deflection potential, a second deflection grid havinginterstices corresponding in size and configuration to said firstdeflection grid and positioned to supplement the deflection produced bysaid first deflection grid, whereby discrete and differing directionsare given to the electron beams from each of said guns.

8. A cathode ray tube for presenting information in color, includingthree electron guns, a target including a plurality of equally spacedtrihedrons each bearing on each of its three faces one of threedifferent phosphors each responsive to electron bombardment to produce aprimary color, and a plurality of grids interposed between said guns andsaid target, said plurality including a parallax grid, a firstdeflection grid and a second deflection grid positioned in that orderalong the line of motion of electrons flowing from said guns to saidtarget, all of said grids having substantially hexagonal apertures ofapproximately equal size, said apertures of said parallax and firstdeflection grids being substantially aligned,

said second deflection grid being positioned with the apertures thereindisplaced from alignment with said first deflection grid one-half anaperture width in one direction and one-half a diagonal length in anorthogonal direction.

9. A cathode ray tube for presenting information in color, including aplurality of electron guns, a target including a plurality ofmulti-hedrons with common orientation in which the sides are at an angletoward the initial direction of the beams from saidguns, and means forcausing impingement of the beams upon the sides substantially normalthereto including an apertured parallax gridbetween the guns and targetfor positioning the beams impinging thereon at similar locations in theapertures thereof, and an electromagnetic deflection grid between theparallax grid and target for deflecting the beams emerging from theparallax grid in a direction substantially normal to the sides, saidelectromagnetic deflection grid including a plurality of elementsdisposed parallel to each other and lying in planes normal to the planeof the parallax grid.

10. For use in a cathode ray tube, a grid combination including aparallax convergence grid and an electromagnetic deflection grid, saidconvergence grid being disposed in a first plane, said electromagneticdeflection grid including deflection elements disposed in a directionnormal to said first plane.

11. A cathode ray tube for presenting information in color, including atleast one electron gun, a parallax grid, at least one deflection gridand a target structure, in that order, said parallax grid and saiddeflection grid being spaced a predetermined distance from each otherand having a predetermined relative orientation, said target structurebearing a plurality of phosphors each producing light energydiflerentfrom that produced by the others upon bombardment by electrons from saidat least one electron gun; said parallax grid comprising a plurality ofinter-connected closed conductive paths.

12. A cathode ray tube for presenting information in color, including atleast one electron gun, a parallax grid, at least one deflection gridand a target structure, in that order, said parallax grid and saiddeflection grid being spaced a predetermined distance from each otherand having a predetermined relative orientation, said target structurebearing a plurality of phosphors each producing light energy differentfrom that produced by the others upon bombardment by electrons from saidat least one electron gun; said parallax grid and said deflection grideach including a plurality of interconnected closed conductive paths.

References Cited in the file of this patent UNITED STATES PATENTS

